(function(doc, win) {
  // 用js动态修改页面跟字体大小
  var docEl = doc.documentElement
  var recalc = function() {
    var clientWidth = docEl.clientWidth
    docEl.style.fontSize = 20 * (clientWidth / 320) + 'px'
  }

  doc.addEventListener('DOMContentLoaded', recalc)
  win.addEventListener('resize', recalc)

})(document, window)